[Surround Sound input/output] Program to make 5.1 input

Firstly, sorry if this is in the wrong section, its a bit hard to know where it fits.

Ok what i have set up is an Xbox 360 connected to my computer monitor on a different input, -Video sorted (all it takes is one button push on the monitor to switch inputs)

But atm whenever i want to use my Logitech 5.1 surround sound for my xbox i have to crawl under the desk and unplug the 3x coaxials and plug them into the component>coaxial adapter to get it working. I've had enough... i tried for a few hours to get my computer to use the excess jacks at the back as inputs (didnt work, if you can help there that's a side question Asus P5Q SE/R MOBO) eventually I gave up and just figured id use the 2 inputs at the front and the one input at the back (therefore 6 channels) and I'd have myself a 5.1 input... I was wrong, i can tie all the inputs together but they are still all just L and R.

I guess basically I'm looking for a program that will let me assign the output channels of the inputs so that i can just have my computer on whenever i want to play xbox and the sound will come through, no crawling around cheers

Frankly, PC's aren't designed for 5.1 inputs over analog; the most they support are 2.0 via the "line in" jack. And I doubt you could assign other jacks an inputs, as soundcards wouldn't know which signal is from which input (L/R, Front, Center etc)

The only way to get 5.1 input is to use SPDIF encoded with a dolby/DTS signal. Alternativly, you could just plug everything into a digital reciever and call it a day.

I have already assigned 3 seperate jacks as inputs as i have shown in the diagram, also the software has picked up and is able to run all the inputs and play them back through the speakers.

All i need is a program that will now let me direct the 6 channels that are coming in to the appropriate speaker and its done, i am yet to find a program like this though... but clearly its not impossible.

I realize this is an old thread, and i do not have a solution to the problem, but I was just wondering what that black box is that takes the 2 RCA inputs and gives 3 TRS outputs, and does this device decode DTS / DD?